1. Field of the Invention
The invention relates to an electric oil pump.
2. Discussion of Background
There is a conventional electric oil pump that is formed by combining a pump with an electric motor that drives the pump. The electric motor includes a rotor that rotates and a stator that is fixed arranged radially outward of the rotor. The rotor is formed by arranging a plurality of permanent magnets on the outer periphery of a rotary drive shaft in the circumferential direction. The rotary drive shaft is shared by the electric motor and the pump. Japanese Patent Application Publication No. 2005-98268 (JP 2005-98268 A) describes a pump in which a stator of an electric motor is fixed to a motor housing with bolts inserted from a pump housing.
However, when the stator of the electric motor is formed by integrally forming coils with bus bars connected to the coils through resin molding, if the pump and the electric motor are fastened to each other with bolts via a resin mold portion, the resin mold portion of the stator, which is in contact with a metal surface of the pump housing, may undergo so-called creep deformation due to, for example, secular change. Thus, deformation of a stator core and loosening of the bolts may occur, and, furthermore, contact noise of a rotor portion of the pump, undesirable operating noise of the electric oil pump due to pulsation of pump discharge pressure or a decrease in pump output may occur.